Javadoc
Indicates that this document has reached an output stage which will
output the document, but hasn't written it to it's output yet. A common
reason for this might be to improve efficiency by doing batch-commits to
a search engine by queueing the documents internally in the output stage,
marking them as Pending instead of Processed until such an action can be
taken.
Functionally the same as marking a document as "processed" in regard to
all other workings of Hydra, with the diagnostic benefit of knowing that
"pending" documents have not been sent to the search engine, in case of a
crash, improper shutdown, or similar.